Ortographic - Auxiliary View

Chapter 3

Orthographic Projection

Basic Topics

Advanced Topics

Exercises

Compiled by : Dzulkifli Awang, PHD

ORTHOGRAPHIC

PROJECTION

AN INTRODUCTION


a system of drawing views of an object using

perpendicular projectors from the object to a

plane of projection

History

• Orthographic Projection was formalized by

Gaspard Monge (b. 1746).

• Monge worked as a drafter in the fortification

design office of the school at Mezier for French

army officers

• His work was kept a military secret for a number

of years until he was allowed to publish in 1795.

• Stone cutters were the first to adopt his

methods. Later carpenters and other trades

abandoned their old methods for orthographic

projection.

Ortho. Projection: Basic Topics

1.1) Engineering Graphics Overview Summary

1.2) Orthographic Projection

1.3) The Glass Box Method

1.4) The Standard Views

1.5) Lines Used in an Orthographic Projection

1.6) Rules for Line Creation and Use

1.7) Creating an Orthographic Projection

Ortho. Proj.: Advanced Topics

1.8) Auxiliary Views

Ortho. Projection: Exercises

Exercise 1-1: Principle views

Exercise 1-2: Line types

Exercise 1-3: Line use in an orthographic

projection

Exercise 1-4: Missing lines 1

Exercise 1-5: Missing lines 2

Exercise 1-8: Drawing an orthographic

projection 1

Exercise 1-9: Drawing an orthographic

projection 2

Ortho. Projection: Exercises

Exercise 1-12: Auxiliary views

Engineering Graphics

1.1) Introduction to Engineering

Graphics


What is Engineering Graphics?

What is an Engineering Drawing?

A drawing that communicates an idea or design.

A set of rules and guidelines that help you

create an Engineering Drawing.


Examples of Engineering Drawings

→ Mechanical Engineers

• Detailed drawing of a part that needs to be

machined.

→ Electrical Engineers

• A circuit schematic.

• Circuit board layout.

→ Civil Engineers

• Plans for a bridge.

• Road layout.


Summary

Summary

What will we learn in Chapter 3?

→ How to create an orthographic projection.

Key points

→ An orthographic projection is a 2-D

representation of a 3-D object.


Orthographic projection is the name given to

the type of drawing where a 3D object is

drawn as 3 different 2D views.

These views are called the Plan (Top),

Elevation (Front) and (Right/Left) End

Elevation.


1.2) Orthographic Projection

Introduction

Introduction

Orthographic projection = 2-D

representation of a 3-D object.

Introduction

An orthographic projection represents

different sides of an object.

The Six Principal Views

The 6 principal

views are

created by

looking at the

object,

straight on, in

the directions

indicated.

Ken

Youssefi

19 Mechanical and

Aerospace

Different Viewpoint

Parallel Projection

Perspective

Parallel


Ken Youssefi 24 Mechanical

and


Standard 2D views

Related Documents

UNITEN

First Angle

Third Angle

Third-angle Projection

First-angle Projection

First and Third Angle Projections

First Angle Projection

Third Angle Projection


1.3) The Glass Box Method

The Glass Box Method

How do we create the 6 principal

views?

The Glass Box Method

Glass Box Method

The object is

placed in a

glass box.

The sides of

the box

represent the

6 principal

planes.

Glass Box Method

The image of

the object is

projected on

the sides of the

box.

Glass Box Method

Things to

notice!

→ The

projection

planes.

→ The

projectors.

→ How

surfaces A

and B are

projected.

Glass Box Method

The box is

unfolded creating

the 6 principal

views.

Ken

Youssefi

38 Mechanical and

Aerospace


Ken

Youssefi

39 Mechanical and

Aerospace

Standard 2D views

Exercise 1-1

Principal Views

Exercise 1-1

Label the 5 remaining principal views with

the appropriate view name.

Name

each

view.

Top

Name

each

view.

Top

Right Side

Name

each

view.

Top

Rear Right Side

Name

each

view.

Top

Rear Left Side Right Side

Name

each

view.

Top

Rear Left Side

Bottom

Right Side

What are the differences

between the Right Side

and Left Side views? Top

Right Side Rear Left Side

Bottom

They are mirror

images with one

different line

type.

What are the differences

between the Top and

Bottom, and Front and

Rear views? Top


Bottom

They are mirror

images with

different line types.

Which view(s) have the

least amount of hidden

or dashed lines?

Top


Bottom

Front and top views.


1.4) The Standard Views

Standard Views

When constructing an orthographic

projection, we need to include enough

views to completely describe the true

shape of the part.

→ Complex part = more views

→ Simple part = less views

Standard Views

The standard views used in an

orthographic projection are;

→ Front view

→ Top view

→ Right side view

The remaining 3 views usually don’t

add any new information.

Standard Views

How many views do we need to

completely describe a block?

Standard Views


completely describe a block?

2 views.

The 3rd view

duplicates

information.

Standard Views


completely describe a sphere?

1 view.

A sphere

has only one

dimension.

Its diameter.

Front View

The front view shows the most features

or characteristics of the object.

→ It usually contains the least amount of

hidden lines.

→ The front view is chosen first and the other

views are based on the orientation of the

front view.

View Alignment

The top and front views are aligned

vertically and share the same width

dimension.

The front and right side views are

aligned horizontally and share the same

height dimension.

Ken

Youssefi

62 Mechanical and

Aerospace

Standard Views of Primitive Solids

Ken

Youssefi

63 Mechanical and

Aerospace

View Orientation

Poor orientation

Good orientation

64

View Selection

Use minimum number of views

to describe the object

Select the most descriptive

views

Conventional Practices

Holes, Ribs & Webs – Principle of Revolution

Conventional Practices

Ken

Youssefi

67 Mechanical and

Aerospace

Conventional Practices -

Intersections

Miter Lines

Miter lines are used to transfer depth information.

O

45o line

drawn from

point O

Standard

multiviews

Conventional Practices - Tangency

Fillets, Rounds & Chamfers

Ken

Youssefi

71 Mechanical and

Aerospace

Top view

Edge Lines – Principal & Inclined

Principal lines appear vertical,

horizontal or as point views. Inclined

lines appear inclined in one view.

2

Edge Lines – Oblique

Oblique line appears

inclined in all views

Principal Planes Principle planes are parallel to principal orthographic

planes

Inclined Planes Inclined planes are perpendicular to two opposite

orthographic planes.

Oblique Planes

Oblique planes are neither parallel nor perpendicular to

any principal orthographic planes.

Type of Planes

Principal

Oblique

Inclined

Edge View of a Plane

Principal planes appear in true

size in one plane and as an

edge view in the other two

planes.


1.5) Lines Types Used in an


Line Type and Weight

Line type and line weight provide

valuable information to the print

reader.

For example, line type and weight can

answer the following questions.

→ Is the feature visible or hidden from view?

→ Is the line part of the object or part of a

dimension?

→ Is the line indicating symmetry?


There are four commonly used line

types;

→ continuous

→ hidden

→ center

→ phantom


Some lines are more important than

others. Importance is indicated by line

weight or thickness.

→ The thicker the line, the more important it is.

Line Types

Visible lines:

→ Visible lines represent visible edges and

boundaries.

→ Continuous and thick (0.5 - 0.6 mm).

Hidden lines:

→ Hidden lines represent edges and

boundaries that cannot be seen.

→ Dashed and medium thick

(0.35 - 0.45 mm).

Line Types

Center lines:

→ Represent axes of symmetry.

→ Long dash – short dash and thin

(0.3 mm).

Line Types

Phantom line:

→ Phantom lines are used to indicate

imaginary features.

• alternate positions of moving parts

• adjacent positions of related parts

→ The line type is long dash – short dash –

short dash and the line weight is usually

thin (0.3 mm).

Line Types

Dimension and Extension lines:

→ Dimension and extension lines are used to

show the size of an object.

• In general, a dimension line is placed between

two extension lines and is terminated by

arrowheads, which indicates the direction and

extent of the dimension.

→ The line type is continuous and the line

weight is thin (0.3 mm).

Line Types

Cutting Plane line:

→ Cutting plane lines are used to show where

an imaginary cut has been made through

the object in order to view interior features.

→ The line type is phantom and the line

weight is very thick (0.6 to 0.8 mm).

→ Arrows are placed at both ends of the

cutting plane line to indicate the direction of

sight.

Line Types

Section line:

→ Section lines are used to show areas that

have been cut by the cutting plane.

→ Section lines are grouped in parallel line

patterns and usually drawn at a 45 angle.

→ The line type is usually continuous and the

line weight is thin (0.3 mm).

Line Types

Break line:

→ Break lines are used to show imaginary

breaks in objects.

→ A break line is usually made up of a series

of connecting arcs.

→ The line type is continuous and the line

weight is usually thick (0.5 – 0.6 mm).

Exercise 1-2

Line types

Example 1-2

Which of the following line types is a

VISIBLE line?

Example 1-2


HIDDEN line?

Example 1-2


CENTER line?

Example 1-2


PHANTOM line?

Example 1-2


DIMENSION & EXTENSION lines?

Example 1-2


CUTTING PLANE line?

Example 1-2


SECTION line?

Example 1-2


BREAK line?

Example 1-2

Notice how different line types are used.

Exercise 1-3

Line use in an orthographic

projection

Exercise 1-3

Fill the following dotted orthographic

projection with the appropriate line types.

Fill in the visible

lines in to top view.

Fill in the visible

lines in to front view.

Fill in the visible lines

in to right side view.

Fill in the hidden

lines in to front, top

and right side views.

Draw the center

lines in all the views.

NOTICE!

The small dashes cross in the

middle.

NOTICE!

The center line connects

between features in the same

view.


1.6) Rules for Line Creation and Use

Rules for Line Creation and Use

The following rules will help us create

lines that communicate effectively.

→ CAUTION! Due to computer automation,

some of the rules may be hard to follow.

Using Hidden Lines

Hidden lines represent edges and

boundaries that cannot be seen.

Creating Hidden Lines

Rule 1:

→ The length of the hidden line dashes may

vary slightly as the size of the drawing

changes.


Rule 2:

→ Hidden lines

should always

begin and end

with a dash,

→ Exception: When

the hidden line

begins or ends at

a parallel visible

or hidden line.


Rule 3:

→ Dashes should join at corners.

Using Center Lines

Center lines represent axes of

symmetry.

→ They are important for interpreting

cylindrical shapes.

Using Center Lines

→ They are also used to indicate circle of

centers, and paths of motion.

Creating Center Lines

Rule 1:

→ Center lines should start and end with long

dashes.


Rule 2:

→ Center lines should intersect by crossing

either the long dashes or the short dashes.


Rule 3:

→ Center lines should extend a short distance

beyond the object or feature.


Rule 4:

→ Center lines may be connected within a

single view to show that two or more

features lie in the same plane.

• CAUTION! Center lines should not extend

through the space between views .

Using Phantom Lines

Phantom lines uses:

→ They may also be used to indicate adjacent

positions of related parts.

Using Phantom Lines

Phantom lines uses:

→ Used to indicate repeated detail.

Using Phantom Lines

Phantom lines uses:

→ They are also used to show a change in

surface direction produced by fillets and

rounds.

Using Phantom Lines

Phantom lines uses:

→ Used to indicate alternate positions of

moving parts.

Creating Phantom Lines

Rule 1:

→ Phantom lines should start and end with a

long dash.

Using Break Lines

Break lines are used to show imaginary

breaks in an object.

Creating Break Lines

There are two types of break lines.

→ If the distance to traverse is short the series

of connecting arcs is used.

Creating Break Lines

There are two types of break lines.

→ If the distance is long the thin straight line

with a jog is used.

Line Precedence

If two lines occur in the same place, the line that is considered to be the least important is omitted.

Lines in order of precedence/importance are as follows;

→ Cutting plane line

→ Visible line

→ Hidden line

→ Centerline


1.7) Creating an Orthographic

Projection

Creating an Orthographic Projection

Choose a front view.

→ Which view shows the most about the

object?

C


Decide how many views are needed.

→ How many and which views?

2

Front

Top

For procedural reasons, we will continue this

example by drawing all 3 standard views.


Draw the

visible

features of

the front

view.


Draw

projectors

off of the

front view.


Draw the

top view.


Project

back to the

front view.


Draw a 45

projector

off the front

view.


Draw

projectors

over to the

45 line

and down.


Draw the

right side

view.


Project

back if

needed.


Draw

centerlines

where

necessary.


Completed Drawing

Projection Symbol

United States = 3rd angle projection

Europe = 1st angle projection

1st Angle & 3rd Angle

Which orthographic projection uses 1st

angle projection and which uses 3rd.

3rd Angle 1st Angle

Exercise 1-4

Missing lines 1

Exercise 1-4

Fill in the missing

lines in the front, right

side, and top views.

1 missing

visible line in

the front view.

The right side

view has 1

missing visible line

and 2 missing

hidden lines.

The top view has

5 missing visible

lines and 2

missing hidden

lines.

Exercise 1-5

Missing lines 2

Exercise 1-5

Fill in the missing

lines in the top, front,

and right side views.

The top view has

1 missing visible

line.

The front view has

4 missing visible

lines and 4

missing center

lines.

The right side

view has 2

missing hidden

lines and 1

missing center

line.

Exercise 1-8

Drawing an orthographic

projection 1

Exercise 1-8

Shade in the surfaces that will appear in the front, top, and right side views.

Estimating the distances, draw the front, top, and right side views.

Identify the surfaces with the appropriate letter in the orthographic projection.

1) Shade in the

surfaces of the front

view.

2) Draw the front

view.

3) Identify the

surfaces.

1) Shade in the

surfaces of the right

side view.

2) Draw the right

side view.

3) Identify the

surfaces.

Notice the

horizontal and

vertical

projectors.

1) Shade in the

surfaces of the top

view.

2) Draw the top

view.

3) Identify the

surfaces.

Notice the 45 deg.

projector

Exercise 1-9

Drawing an orthographic

projection 2

Exercise 1-9

Identify the best

choice for the front

view.

Estimating the

distances, draw the

front, top, and right

side views.

Front view = A


1.8) Auxiliary Views

Auxiliary Views

Auxiliary views are used to show the true

shape of features that are not parallel to

any of the principle planes of projection. Aligned with the

angled surface

Partial

auxiliary

view

Skip advanced topic

Exercise 1-12

Auxiliary View

Exercise 1-12

Draw the auxiliary

view for this object.


End

• THANK YOU FOR YOUR ATTENTION.

• NOW…START DOING YOUR

EXERCISES…

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